Hmmm let's see
The most memorable are definitely my team's first ever TWL Alpha and CAL matches against united 5 (2005) that had just placed #2 at QuakeCon barely losing in the finals to check 6. We got steam rolled both games as we were new to competition However, playing 1 of the best teams in the world was definitely a lesson that we needed in order to get better.
Then i would have to mention the last season of TWL #10 (2007) where we rolled through Warped Sanity and Gameface (champs for the past 3 seasons in a row) and had to face team Excel in the finals where we barely lost 1 map and then the game. http://challenge-tv.com/demos/view/33856
Then I'd put an american 1 day cup where we beat united 5's returning roster and then trolled our final match vs SNL. > random clip Slurpee made after the game with u5 http://www.own3d.tv/Ceres/video/652371
Oh, I'd also mention STA season #10 where we beat SNL thanks to them forgetting to call Night, urtier and senji, thus playing us with an all american lineup and losing < we also won that STA season beating sandals after that in a very boring and one sided game.
I could also mention smurfing in many Nations cup matches for both team USA and Canada. Those were always fun with decent players playing.
Other random moments might be a lot of scrims where we managed to win against top teams but then fail hard during matches against the same teams.
I almost forgot one of our season 1 or 2 matches in competition where we had to play team Unfaithful and they were supposed to beat us easily and even spawn camp us (according to the predictions)
We ended up full holding them on the Supply flag during the 1st map and they pretty much gave up. http://img51.imageshack.us/img51/3624/201206202212.jpg